The chage command lets root set password aging - how long a user can use a password without changing it. With "-l" and a user name, it lists the settings. My bet is that most systems produce listings like this:
Minimum: 0 Maximum: 99999 Warning: 7 Inactive: -1 Last Change: Oct 25, 2004 Password Expires: Never Password Inactive: Never Account Expires: Never
In other words, they aren't using password aging.
I'm of divided mind on this issue. On the one hand, the value of changing passwords seems obvious: passwords do leak out over time, so it seems prudent to change them. Also, if someone is trying brute-force password guessing, the longer a password remains in use, the more chance of guessing it. On the other hand, when passwords remain the same, users may actually be able to remember them, while constant change just leads to yellow sticky notes plastered on monitors; a practice obviously far less secure than an unchanged password in someone's memory.
Obviously the real answer is that passwords have to go. Identity cards, iris scans, voice recoginition: who knows what the final answer will be, but it can't be passwords.
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More Articles by Tony Lawrence © 2012-07-17 Tony Lawrence
Much to the surprise of the builders of the first digital computers, programs written for them usually did not work. (Rodney Brooks)